Circuit interrupter



Jan. 24, 1956 A. G. STEINMAYER 2,732,453

CIRCUIT INTERRUPTER Filed April 7, 1953 2 Sheets-Sheet l INVENTOR. fl/win k leinmizyer United States Patent CIRCUIT INTERRUPTER Alwin G. Steinmayer, Milwaukee, Wis., assignor to McGraw Electric Company, Milwaukee, Wis., a corporation of Delaware Application April 7, 1953, Serial No. 347,326 6 Claims (Cl. 200-146) This invention relates to circuit interrupters, and particularly to electrical, switching mechanisms that may be used on high tension lines, and which are adapted to be opened under load conditions without damaging integral parts or associated apparatus.

Very often power lines are isolated or sectionalized with the use of disconnect switches, or oil circuit breakers. The former are intended to be opened primarily when there is no load on the line, and the latter are used for opening lines under relatively heavy load. Oil circuit breakers are comparatively more expensive than discon nect switches. In addition, it often becomes necessary to open electrical lines under load at points located at remote and inconvenient distances from the circuit breaker. When the ordinary type disconnect switch is opened under load, the contacts are usually damaged by arcing and burning and there is the everpresent possibility of producing a surge in the line accompanied by a flashover to ground.

In recent years contributions to the circuit interrupter field have been directed to auxiliary interrupters that operate in conjunction with disconnect switching mechanisms. The auxiliary interrupters are electrically connected in the circuit in parallel relationship to the main switch connection, and are arranged to have the current momentarily transferred thereto during the period that the main switch blades are being opened. The auxiliary circuit is thereafter opened following a predetermined delay and any arcs that might be established on separation of the auxiliary interrupter contacts are properly and effectively extinguished in an arc extinguishing media.

It is an object of the present invention to provide a circuit interrupter for use with conventional switching devices, which interrupter is in normally closed circuit position and forms a part of a parallel electrical circuit with said switch devtice, and which is arranged to momentarily receive the entire electrical load until the switch device has been operated to fully separate its load connection, and further, which interrupter is arranged to interrupt the load in a media where it will be extinguished and expelled by a combined throttling action and accompanying gas pressure created by an arcing of the load.

it is another object of this invention to provide an auxiliary circuit interrupter for an electrical switch which is arranged for parallel electrical connection with said switch, and which interrupter includes a housing having an annular opening defined by material comprising an arc extinguishing and expelling media having a stationary line terminal adjacent thereto, said terminal being arranged for separable electrical engagement with a rotatable contact member biased towards engagement with said terminal and rotatably positioned on a shaft concentric with the axis of said annular opening.

It is a specific object of the present invention to provide a circuit interrupter including a housing having an annular opening defined by an arc extinguishing material Patented Jan. 24, 1956 and opposed stationary terminals projecting therethrough, each engageable with a rotatable contact member biased towards engagement with said stationary terminals.

For a more complete understanding of the nature and scope of this invention, reference may be had to the following detailed description taken in connection with the accompanying drawings, in which:

Fig. l is a view partly in elevation and partly in diagram of the circuit interrupter in electrical connection with a main switch means interposed in a power line.

Fig. 2 is a longitudinal sectional view of the circuit interrupter.

Fig. 3 is a cross sectional view taken on line 3-3 of Fig. 2.

Referring to the drawings, especially Fig. 1, the interrupter, or load break device, is generally denoted by the reference character 1 and is electrically connected to the power line 2 from line terminals 3 and 4, which connection bypasses the main switch means 5. A direct mechanical connection with the switch means 5 is made with an actuator member 6 through a pivot member 7 to a crank 8. The pivot member 7 is integral with the crank 8 and is grooved to receive the hooked end of a tension spring 9. The spring 9, which is shown under tension in Figs. 1 and 2, is attached at the opposite end to a projecting pin 10 integral with a sectoral supporting plate 11. The plate is .attached to the cover plate 12 by means. of spaced. conventional machine screws 13, which are preferably countersunk to provide a flush fit. Stop members 14 and 15 are provided by integral projections on the plate 11, andare each engageable with the crank 8 as will hereinafter be described.

Referring particularly to Fig. 2 and Fig. 3, it will be seen that the crank isdirectly connected to a rotating drtun 20 by means of a face plate 21 and a machine screw 22. The entire unit including the crank 8 and the drum 20 is freely rotatable in the bore of the bearing 23. A tubular insulating member 24 is positioned diametrically in opposed openings in the insulating drum 20. The member 24 is provided with a coextensive bore for receiving movable contacts 25 and 26, which are elec trically connected with one another by means of a flexible cable 27. The contact members 25 and 26 are slidable within the bore of the tubular member 24 and are biased towards opposed outward movement by the compression spring 28 which is positioned circumjacent to the flexible connector 27 and engageable with shoulder portions on the contacts provided by reduced diameter projections 29 and 30, respectively.

The cover plate 12 is fastened to a tubular housing member 31, which may be provided from canvas-based Bakelite stock. The tubular member 31 may be lined internally with a horn fiber. liner 32 arranged to receive stationary contacts 33 and 34..

It will be noted that the member 31 may entirely consist of arc extinguishing material or other insulating material capable of withstanding arcing conditions, or that a sectoral portion of the liner 32 or member 31 may comprise such material provided it lies in the path of the movable rotating contacts 25 and 26 immediately following separation. The movable contacts 25 and 26 are normally electrically engaged with contacts 33 and 34, respectively. It is preferable to leave the external parts exposed to'the atmosphere without a backing member for purposes hereinafter described.

In describing the operation of the present invention, it will be assumed that the main switch means 5 is closed to providea closed electrical circuit in the power line 2. Allof the operating parts arein the position shown in Figs. 1 and 2. 7 That is, the auxiliary interrupter or load break device Lalso closes a parallel circuit through contacts 25 and 26 in engagement with contacts 33 and 34. The parallel circuit is intended to'only momentarily carry the entire load current for a" predetermined period after the main switch is opened. The main switch means is preferably designed to carry substantially the entire load when both circuits are in electrical connection.

It is to be noted that the tension spring 9 biases the crank 8 towards the stop 14 in over-toggle position which will retain the movable contacts in normal electrical and mechanical engagement with the stationary contacts. The over-center arrangement is designed to provide a snap action to the moving parts, in addition to providing a predetermined time delay. It will be obvious that the time delay may be provided in any of many ways, such as with a dashpot, or the like (not shown). The time delay is deemed necessary to provide a momentary period between the opening of the main switch means 5 and the separation of the movable contacts 25 and 26 from the stationary terminals 33 and 34, respectively. Thus, for a predetermined length of time prior to movement of contact members in the load break de vice 1, the main switch means will be opened and the entire load will be transferred to the load break device. Thus, the main switch device will be opened without arcing and consequent burning of contacts and damage to associated parts. The entire load is transferred to the parallel circuit, including the circuit interrupter or' load break device 1, where any arcing may occur in a media which acts to de-ionize, extinguish and expel any are created therein.

Assuming now that the switch blade of the main switch means 5 is being opened under conventional practice. The blade will cause the actuator 6 to rock the crank 8 on its axis in a clockwise direction, as shown in Fig. 1, against the action of the tension spring 9. During the period that it takes the pivot 7 to move the crank 8 from the stop 14 past its center, the main switch blades will be opened and the load transferred to the load break device 1. When the pivot 7 passes center the crank will provide a snap-action until it rests at the stop 15 with the contacts entirely separated from one another.

During the period transpiring as the crank moves from stop 14 to the stop 15, the integrally attached insulated drum 20 will rotate in the bearing 23 and will cause movable contacts 25 and 2:6 to be disengaged from the stationary contacts 33 and 35, respectively. Inasmuch as either the drum or the liner 32, or both are preferably made of an arc extinguishing material, such as horn fiber, any arc that is created during the separation of the contacts will be confined between the drum 20and the liner 32, and will are on these members to formv hot gases and water'vapor. The gases and vapor are un-i'oni zed and will be expelled by the rotational motion between the liner" and the drum toatmosphere. As shown, the drum is preferably tapered'to provide gradually distended openings 40 and 41', which further act to create effective ex pulsion pressures. When it is desired to close the circuit in the line 2, the main switch blade of the switch 5 may be closed and the crank 8 of the load break device I returned to its normal operating position, as shown in Figs. l and 2, with the spring 9 biasing the crank towards the stop 14. This may be done automatically by conventional methods using known resetting mechanisms (not shown), or manually after' the main switch means 5 is closed.

It will be seen that a novel circuit interrupter has been provided, which is adapted to be opened under load condition and may be'positioned in a high tension power line. The interrupter may be operated effectively in conjunction witha disconnecting switch, which ordinarily is not adapted to be opened under load conditions; In addition, the invented'circuit interrupter or load break device, contemplates a complete confinement of any deleterious arcing conditions, which might prove damaging to the main switch structure or surrounding equipmentu The novel load break device is readily adaptable to existing switch structures, requiring little modification of these structures.

I claim:

1. A circuit interrupter comprising a tubular housing having a bore, a tubular insulating liner. in said bore concentric with the longitudinal axis of said tubular housing, stationary contact members communicating with said bore and lying in a plane substantially normal to said longitudinal axis and in diametrically opposed relationship with one another, a rotatable insulating member concentric with and journaled at the longitudinal axis of said bore, said rotatable member including a pair of movable contact members electrically connected with one another and lying substantially in the same plane as said stationary contact members, said rotatable insulating member comprising an arc-extinguishing material capable of evolving un-ionized cooling gases in the presence of an arc, spring means biasing said movable contact members towards electrical engagement with said opposed stationary contact members, and an over-center toggle biasing means for providing a quick-break separation of said movable contact members with said stationary contact members.

2. A load break switching mechanism consisting of a main switch means for electrically connecting and disconnecting an electric line and an auxiliary circuit interrupter normally in parallel circuit relation to said main switch means and adapted to carry the entire load for an interval after said main switch means is operated to disconnect said electric line, said circuit interrupter comprising a tubular housing having a bore, a tubular insulating liner in said boreconcentric with the longitudinal axis of said tubular housing, stationary contact members communicating with said bore and lying in a plane substantially normal to said longitudinal axis and in diametrically opposed relationship with one another, a rotatable insulating member concentric with and journaled at the longitudinal axis of said bore, said rotatable member including a pair of movable contact members electrically connected with one another and lying substantially in the same plane as said stationary contact members, said rotatable insulating member comprising an arc-extinguishing material capable of evolving un-ionized cooling gases in the presence of an arc, spring means biasing said movable contact members towards electrical engagement with said opposed stationary contact members, and an overcenter toggle biasing means for providing a quick-break separation of said movable contact members with said stationary contact members.

3. A circuit interrupter comprising a tubular housing having a bore, a stationary contact communicating with said bore, a rotatable insulating member concentric with and j'ournaled at the longitudinal axis of said bore, said rotatable member including a movable contact biased towards electrical engagement with said stationary confact, the outer surface of said rotatable insulating memher and the surface of said bore jointly defining a tapered concentric passage thereb'etween, said passage having a constricted transverse cross-sectional delineation in the proximity of said contacts, the cross-section of said passage being relatively distended at a portion longitudinally spaced from said constricted cross-sectional delineation, at least one defining surface of said concentric passage comprising an arc-extinguishing material capable of evolving un-ionized cooling gases in the presence of an arc.

4. A circuit interrupter comprising a tubular housing having a bore, a stationary contact communicating with said bore, a rotatable insulating member concentric with and journaled at the longitudinal axis of said bore, said rotatable member including a movable contact biased towards electrical engagement with said stationary contact, the outer surface of said rotatable insulating member and the surface of said bore jointly defining a tapered concentric passage, said passage being relatively distended in cross-section at its opposite ends and further defining a relatively constricted'transverse cross-sectional delinea' tion at a portion intermediate its ends in the proximity of said contacts, at least one defining surface of said concentric passage comprising an arc-extinguishing material capable of evolving tin-ionized cooling gases in the presence of an arc.

.5. A load break switching mechanism consisting of a main switch means for electrically connecting and dis connecting an electric line and an auxiliary circuit interrupter normally in parallel circuit relation to said main switch means and adapted to carry the entire load for an interval after said main switch means is operated to disconnect said electric line, said circuit interrupter comprising a tubular housing having a bore, a stationary contact communicating with said bore, a rotatable insulating metnber concentric with and journaled at the longitudinal axis of said bore, said rotatable member including a movable contact biased towards electrical engagement with said stationary contact, the outer surface of said rotatable insulating member and the surface of said bore jointly defining a tapered concentric passage therebetween, said passage having a constricted transverse cross-sectional delineation in the proximity of said contacts, the crosssection of said passage being relatively distended at a portion longitudinally spaced from said constricted crosssectional delineation, at least one defining surface of said concentric passage comprising an arc-extinguishing mate rial capable of evolving un-ionized cooling gases in the presence of an arc.

6. A load break switching mechanism consisting of a main switch means for electrically connecting and disconnecting an electric line and an auxiliary circuit interrupter normally in parallel circuit relation to said main switch means and adapted to carry the entire load for an interval after said main switch means is operated to disconnect said electric line, said circuit interrupter comprising a tubular housing having a bore, a stationary contact communicating with said bore, a rotatable insulating member concentric with and journaled at the longitudinal axis of said bore, said rotatable member including a movable contact biased towards electrical engagement with said stationary contact, the outer surface of said rotatable insulating member and the surface of said bore jointly defining a tapered concentric passage, said passage being relatively distended in cross-section at its opposite ends and further defining a relatively constricted transverse cross-sectional delineation at a point intermediate its ends in the proximity of said contacts, at least one defining surface of said concentric passage comprising an arc-extinguishing material capable of evolving urn-ionized cooling gases in the presence of an arc.

References Cited in the file of this patent UNITED STATES PATENTS 2,144,414 Milliken Jan. 17, 1939 2,337,889 Harlow et al Dec. 28, 1943 2,542,088 Krieger Feb. 20, 1951 2,568,470 Titus Sept. 18, 1951 2,599,242 Favre June 3, 1952 

